import math def quadratic(a,b,c): if not isinstance(a,(int ,float)): raise ("a is not a number") if not isinstance(b,(int,float)): raise ("b is not a anumber") if not isinstance(c,(int,float)): raise ("c is not a anumber") d = b * b - 4 * a * c if a==0: return ('a不能为0') if b==0: if c==0: return '方程根为全体实数' else: return '方程无实数根' else: x=(-b)/(2*a) return '方程只有一个实数根',x else: if d>0: x1=(-b+math.sqrt(d))/(2*a) x2=(-b-math.sqrt(d))/(2*a) return x1,x2 elif d<0: return '方程无实根' print(quadratic(2,3,1))